//登录
var loginBtn=document.querySelector('header section div.member div')
console.log(loginBtn);
loginBtn.onclick=function(){
    var loginDialog=document.querySelector('section.login')
    loginDialog.style.visibility='visible'
}
//隐藏
var loginCloseBtn=document.querySelector('section.login i.icon-close')
loginCloseBtn.onclick=function(){
    var loginDialog=document.querySelector('section.login')
    loginDialog.style.visibility='hidden'
}
    var loginblueBox=document.querySelector('section .login')
    loginblueBox.onmousedown=function(evt){
        var oldE=evt||window.event
        document.onmousemove=function(evt){
         var e=evt||window.event
         var left=e.clientX-e.oldE.offsetX
         var top=e.clientY-e.oldE.offsetY
         var loginDialog=document.querySelector('section.login')
         loginDialog.style.position='absolute'
         loginDialog.style.left=left+'px'
         loginDialog.style.top=top+'px'
            document.onmouseup=function(){
            document.onmousemove=null
            }
        }
    }